Copper vs. Silver interconnects

We are running two systems from one CD player. We have a SET (tube, obviously) amp, a hybrid (tube outstage) amp, and the CD player also has a tube. I love my Verastarr silver reference interconnects, but it's always fun to try out different cables.

I have listened to a variety of copper cables (Kimber, DH Labs, Analysis Plus, Harmonic Technology, etc.), and I find them to lack the clarity and lively authority of the silver cables in these particular systems.

My question is this: do I stick with the silver cables (or gold, palladium, beryllium, etc.), or are their some copper interconnects that would really be worth trying? I'm asking for your collective expertise/experience on this one, as I don't want to continue going through the process of buying and selling cables that are only going to sound veiled and/or dull in comparison to the Verastarr's.

Thank you for the input.